The advent of mobile communication technology has led to the proliferation of radiotelephones (also known as wireless telephone). Now, a person can carry with them a radiotelephone anywhere they go. A person can make a telephone call from almost anywhere to another person and can also receive a telephone call from anywhere.
Radiotelephones are generally linked to the Public Switched Telephone Network (PSTN) through a network of antennas, base stations, and mobile switching centers. Each radiotelephone is in communication with at least one antenna and switches from one antenna to another when it moves from one antenna cell to another antenna cell. This “cellular” infrastructure will be utilized for my invention to transmit the sensors information through the PSTN switching centers, to the processing centers.
My technique, based upon signal (radiation) strength and trilaterialization can be employed, but they are generally effective in line-of-sight conditions, such as rural settings.
In dense urban areas, radioactive waves reflect on buildings before reaching a receiving antenna on a mobile device, and the mobile device receives radioactive signals both directly from an emitting antenna and from reflections. This phenomenon is known as multipath signals, and it is well known in the wireless telephony art. The multipath phenomenon renders most analytical location computational techniques such as time-of-arrival (TOA) or time-difference-of-arrival (TDOA) substantially useless in urban areas. Radiation (different frequencies) may have the same characteristics.